The image processor is represented as the multi-functional printer combining respective functions of a copying machine, a scanner, a printer, and a facsimile, or respective functions of a facsimile and a copying machine and a printer. Such image processor comprises an image reader for reading images such as shapes and positions of characters and graphic patterns drawn on a paper or a sheet-like recording medium (which is called an original hereafter).
FIG. 15 shows an example of the image reader applied to the copying machine.
First, an original 117 placed on an original tray 118 comprising an original carrier 101 is drawn into a machine casing by a picking roller 119, and then fed to a read station 106 by an upper and lower feeding rollers 102a and 102b. The original 117 fed to the read station 106 in this way is carried forwarder by a belt roller 103 placed on the upper side of a transport path 114 of the original.
At a reading position P of the read station 106, the images drawn on one side of the original 117 is read out. After completing the reading, the belt roller 103 carries the original 117 from the read station 106 to a reversing roller 104. After the reversing roller 104 makes the original 117 turn over, the original 117 is carried to the read station 106 again by the belt roller 103 of which the rotation direction is reversed. The read station 106 reads the images drawn on the other side of the original 117, and then the original is discharged outside of the copying machine.
The read station 106 is provided with an image reader in which the original 117 is irradiated with the light from a light source 112 like a fluorescent light at the reading position P, and then the reflected light is guided to a lens 109 through a mirror 113 and is focused on a sensor 108 like CCD.
Though in the above description the light source without moving itself is to read the original 117 moving in the transport path 114, there is an other configuration: the glass original table (not shown in the drawing) is provided at the position below the transport path 114, and the original placed on this original table is read out by moving the light source 112 (the reading position P as well as the light source 112). Such configuration is available for obtaining image data from the original that cannot be inserted into the original tray 118, such as a book, for example.
FIG. 16 is a diagram showing an example of related arts of the image reader different from the above-mentioned one. As shown in FIG. 16, the image reader is a contact type image reader comprising light receiving means 126 provided with a lens using a rod lens array 121 and a sensor 108 using CCD or the like, in addition to the light source 112 of LED array and etc.
The LED array used as the light source 112 is configured by disposing a plurality of LED element 125 at specific intervals on one side of a basal plate 124 as shown in FIG. 17, for example.
On the light source 112, the each LED array is placed symmetrically so that the illuminance of the light of the LED array may reach the peak at the reading position P of the original 117.
The rod lens array 121 is placed above the reading position P of the original 117. The rod lens array 121 is configured as shown in FIG. 18: a specific number of rod lenses 122, which is in a specific length and in a cylindrical shape of a specific diameter, may be disposed in a plurality of line so as to adjoin to each other. And such configured rod lens 122 is put between basal plates 124 through a black resin used as a light-absorbing layer 123 for removing the light noises of the crosstalk and the flared light.
At this time, as the angular aperture that is an angle between the central axis of the rod lens 122 and the light incident on the rod lens 122 gets smaller, the focal depth of the incident light becomes deeper. When the focal depth becomes deep, it is possible to obtain a clear picture within a specific area from the focus of the rod lens 122 as much as the one at the focus position. It is equivalent to the improvement of the image quality. In other words, in order to improve the image quality, it is necessary to narrow the angular aperture. To achieve this object, the rod lens 122 may be small in the outside diameter of circle.
The crosstalk is a phenomenon that in case where the reflected light on the original 117 is incident to the central axis of the rod lens 122 of the rod lens array 121 over specific angles, the reflected light is not reflected on the side surface of the cylinder of the rod lens 122 but penetrates into the other adjacent rod lens. Accordingly, the reflected light does not converge on a position to be converged, but is detected as the noises by the sensor 108.
The flared light is the irregular reflection of light on the original 171, and the phenomenon exerts the bad influence upon the positions other than that to be converged. It is also detected as the noises by the sensor 108.
The sensor 108 is CCD, CMOS (Complementary Metal Oxide Semiconductor), or the like, for example. It is needless to say that it is placed on the opposite side to the original of the rod lens array 121.
One of the demerits of the conventional image processor like the above copying machine is that the device becomes big in size because the copying machine must be provided with the reversing roller 104 due to reading the original 117 per one side. In addition, there are other demerits that the rotation direction of the belt roller 103 must be controlled so as to reverse the rotation direction corresponding to the reading surface of the original 117 and it takes long time for the reading.
If the contact type of image reader is adopted, it is possible to downsize the image processor further more than a case of adopting the image reader using the mirror and lens. Even in the contact type of image reader, the optical path length requires approximately 50 mm by adopting the rod lens 122 in 0.6 mm diameter.
The diameter of the rod lens 122 used for the light receiving means 126 may be small in order to shorten the focal length (shorten the optical path length) of the contact type of image reader. However, the smaller the diameter of the rod lens 122 becomes, the more conspicuous the crosstalk and the flare phenomenon becomes. It makes impossible to obtain clear images.
FIGS. 19A and 19B are graphs showing the distribution of the illuminance of the conventional image reader provided with the LED array as the light source 112. In case where the reading direction is the sub scanning direction as described previously, if the illuminance is distributed around the irradiated position so as to form a peaked shape, the distribution of the illuminance on the original 117 when it is positioned at the reading position P can be shown as in FIG. 19A. On the other hand, under a state where the original 117 shifts in the direction away from the light source 112 at the reading position P, the distribution of illuminance is shown in FIG. 19B.
That is to say, the position away from the peak of the distribution of illuminance becomes the reading position P, accordingly while keeping the illuminance small the reading is performed. In case where the fluorescent light is used as the light source 112 as described above, the light intensity is strong originally. And the illumination width is wide, so that the influence on the image quality at the copying is less even when the original shifts more or less. However, in order to downsize the image reader, LED and the electronic luminescence used as the light source has a comparative small light intensity, and the light with narrow illumination width must be used.
If the device works on the basis of the above-mentioned distribution of illuminance in this case, it is not possible to obtain the sufficient image quality.
It is noted that when the image reader reads the images drawn on the original 117, the direction that the original is read at a time at the reading position P is the main scanning direction, the direction that the original is read one after another corresponding to the carrying direction of the original is the sub-scanning direction.
The invention is proposed considering the above-mentioned conditions, and has an object to provide the image processor capable of downsizing the image reader, shortening the time for reading the images drawn on the both sides of the original, and avoiding the deterioration of image quality accompanying with the downsizing, the image reader and the fiber lens thereof, and the method of manufacturing the fiber lens.